8-Speed Transmissions

ABSTRACT

The transmission has a plurality of members that can be utilized in powertrains to provide eight forward speed ratios and one reverse speed ratio. The transmission includes three planetary gear sets, six torque-transmitting devices, two fixed interconnections and a grounded member. The powertrain includes an engine and torque converter that is continuously connected to one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The six torque-transmitting devices provide interconnections between various gear members, and the transmission housing, and are operated in combinations of two to establish eight forward speed ratios and one reverse speed ratio.

TECHNICAL FIELD

The present invention relates to a power transmission having threeplanetary gear sets that are controlled by six torque-transmittingdevices to provide eight forward speed ratios and one reverse speedratio.

BACKGROUND OF THE INVENTION

Passenger vehicles include a powertrain that is comprised of an engine,multi-speed transmission, and a differential or final drive. Themulti-speed transmission increases the overall operating range of thevehicle by permitting the engine to operate through its torque range anumber of times. The number of forward speed ratios that are availablein the transmission determines the number of times the engine torquerange is repeated. Early automatic transmissions had two speed ranges.This severely limited the overall speed range of the vehicle andtherefore required a relatively large engine that could produce a widespeed and torque range. This resulted in the engine operating at aspecific fuel consumption point during cruising, other than the mostefficient point. Therefore, manually-shifted (countershafttransmissions) were the most popular.

With the advent of three- and four-speed automatic transmissions, theautomatic shifting (planetary gear) transmission increased in popularitywith the motoring public. These transmissions improved the operatingperformance and fuel economy of the vehicle. The increased number ofspeed ratios reduces the step size between ratios and therefore improvesthe shift quality of the transmission by making the ratio interchangessubstantially imperceptible to the operator under normal vehicleacceleration.

Six-speed transmissions offer several advantages over four- andfive-speed transmissions, including improved vehicle acceleration andimproved fuel economy. While many trucks employ power transmissionshaving six or more forward speed ratios, passenger cars are stillmanufactured with three- and four-speed automatic transmissions andrelatively few five or six-speed devices due to the size and complexityof these transmissions.

Seven-, eight- and nine-speed transmissions provide further improvementsin acceleration and fuel economy over six-speed transmissions. However,like the six-speed transmissions discussed above, the development ofseven-, eight- and nine-speed transmissions has been precluded becauseof complexity, size and cost.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improvedtransmission having three planetary gear sets controlled to provideeight forward speed ratios and one reverse speed ratio.

The transmission family of the present invention has three planetarygear sets, each of which includes a first, second and third member,which members may comprise a sun gear, a ring gear, or a planet carrierassembly member, in any order.

In referring to the first, second and third gear sets in thisdescription and in the claims, these sets may be counted “first” to“third” in any order in the drawing (i.e., left to right, right to left,etc.). Additionally, the first, second or third members of each gear setmay be counted “first” to “third” in any order in the drawing (i.e., topto bottom, bottom to top, etc.) for each gear set.

Each carrier member can be either a single-pinion carrier member(simple) or a double-pinion carrier member (compound). Embodiments withlong pinions are also possible.

A first interconnecting member continuously connects a member of thefirst planetary gear set with a member of the second planetary gear set.

A second interconnecting member continuously connects a member of thesecond planetary gear set with a member of the third planetary gear set.

The sun gear member of the first planetary gear set is continuouslyconnected to a stationary member (transmission housing/casing). Theinput member is continuously connected with the sun gear member of thesecond or third planetary gear set. The output member is continuouslyconnected with the planet carrier assembly member or ring gear member ofthe third planetary gear set.

A first torque-transmitting device, such as a brake, selectivelyconnects the planet carrier assembly member of the second or thirdplanetary gear set with a stationary member (transmissionhousing/casing).

A second torque-transmitting device, such as a clutch, selectivelyconnects the planet carrier assembly member of the first planetary gearset with the planet carrier assembly member of the second planetary gearset. Alternatively, a second torque-transmitting device, such as abrake, selectively connects the sun gear member of the third planetarygear set with a stationary member (transmission housing/casing).

A third torque-transmitting device, such as a clutch, selectivelyconnects the planet carrier assembly member of the first planetary gearset with the sun gear member of the third planetary gear set orselectively connects the ring gear member of the first planetary gearset with the ring gear member of the third planetary gear set.

A fourth torque-transmitting device, such as a clutch, selectivelyconnects the planet carrier assembly member of the first planetary gearset with the planet carrier assembly member of the third planetary gearset or with the ring gear member of the third planetary gear set.

A fifth torque-transmitting device, such as a clutch, selectivelyconnects the ring gear member of first planetary gear set with the ringgear member of the second planetary gear set or with the sun gear memberof the third planetary gear set.

A sixth torque-transmitting device, such as a clutch, selectivelyconnects the ring gear member of the first planetary gear set with theplanet carrier assembly member of the third planetary gear set orselectively connects the ring gear member of the second planetary gearset with the sun gear member of the second planetary gear set.

The six torque-transmitting devices are selectively engageable incombinations of two to yield eight forward speed ratios and one reversespeed ratio.

Optionally, the ring gear member of one of the planetary gear sets maybe a split ring gear member having a first and a second portion therebyallowing the planet carrier assembly member of the planetary gear set tobe selectively connectable to other members of the planetary gear setbetween the first and second portions of the split ring gear.

A variety of speed ratios and ratio spreads can be realized by suitablyselecting the tooth ratios of the planetary gear sets.

The above features and other features and advantages of the presentinvention are readily apparent from the following detailed descriptionof the best modes for carrying out the invention when taken inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 a is a schematic representation of a powertrain including aplanetary transmission in accordance with the present invention;

FIG. 1 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 1 a;

FIG. 1 c is a schematic representation of the powertrain of FIG. 1 adepicted in lever diagram form;

FIG. 2 a is a schematic representation of another embodiment of apowertrain including a planetary transmission in accordance with thepresent invention;

FIG. 2 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 2 a; and

FIG. 2 c is a schematic representation of the powertrain of FIG. 2 adepicted in lever diagram form.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, there is shown in FIG. 1 a a powertrain 10having a conventional engine and torque converter 12, a planetarytransmission 14, and a conventional final drive mechanism 16. The engine12 may be powered using various types of fuel to improve the efficiencyand fuel economy of a particular application. Such fuels may include,for example, gasoline; diesel; ethanol; dimethyl ether; etc.

The planetary transmission 14 includes an input member 17 continuouslyconnected with the engine 12, a planetary gear arrangement 18, and anoutput member 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 18 includes three planetary gear sets20, 30 and 40.

The planetary gear set 20 includes a sun gear member 22, a ring gearmember 24, and a planet carrier assembly member 26. The planet carrierassembly member 26 includes a plurality of pinion gears 27 rotatablymounted on a carrier member 29 and disposed in meshing relationship withboth the sun gear member 22 and the ring gear member 24.

The planetary gear set 30 includes a sun gear member 32, a ring gearmember 34, and a planet carrier assembly member 36. The planet carrierassembly member 36 includes a plurality of pinion gears 37 rotatablymounted on a carrier member 39 and disposed in meshing relationship withboth the ring gear member 34 and the sun gear member 32.

The planetary gear set 40 includes a sun gear member 42, a ring gearmember 44, and a planet carrier assembly member 46. The planet carrierassembly member 46 includes a plurality of pinion gears 47 mounted on acarrier member 49 and disposed in meshing relationship with both thering gear member 44 and the sun gear member 42.

The planetary gear arrangement also includes six torque-transmittingdevices 50, 52, 54, 55, 56 and 57. The torque-transmitting device 50 isa stationary-type torque-transmitting device, commonly termed brake orreaction clutch. The torque-transmitting devices 52, 54, 55, 56 and 57are rotating-type torque-transmitting devices, commonly termed clutches.

The input member 17 is continuously connected with the sun gear member42 of the planetary gear set 40. The output member 19 is continuouslyconnected with the planet carrier assembly member 46 of the planetarygear set 40. The sun gear member 22 of the planetary gear set 20 iscontinuously connected with the transmission housing 60.

A first interconnecting member 70 continuously connects the ring gearmember 24 of the planetary gear set 20 with the sun gear member 32 ofthe planetary gear set 30. A second interconnecting member 72continuously connects the ring gear member 34 of the planetary gear set30 with the ring gear member 44 of the planetary gear set 40.

A first torque-transmitting device, such as brake 50, selectivelyconnects the planet carrier assembly member 36 of the planetary gear set30 with the transmission housing 60. A second torque-transmittingdevice, such as clutch 52, selectively connects the planet carrierassembly member 26 of the planetary gear set 20 with the planet carrierassembly member 36 of the planetary gear set 30. A thirdtorque-transmitting device, such as clutch 54, selectively connects theplanet carrier assembly member 26 of the planetary gear set 20 with thesun gear member 42 of the planetary gear set 40. A fourthtorque-transmitting device, such as clutch 55, selectively connects theplanet carrier assembly member 26 of the planetary gear set 20 with theplanet carrier assembly member 46 of the planetary gear set 40. A fifthtorque-transmitting device, such as clutch 56, selectively connects thering gear member 24 of the planetary gear set 20 and the sun gear member32 of the planetary gear set 30 via interconnecting member 70 with thering gear member 34 of the planetary gear set 30 and the ring gearmember 44 of the planetary gear set 40 via interconnecting member 72. Asixth torque-transmitting device, such as clutch 57, selectivelyconnects the ring gear member 24 of the planetary gear set 20 and thesun gear member 32 of the planetary gear set 30 via interconnectingmember 70 with the planet carrier assembly member 46 of the planetarygear set 40.

As shown in FIG. 1 b, and in particular the truth table disclosedtherein, the torque-transmitting devices are selectively engaged incombinations of two to provide eight forward speed ratios and onereverse speed ratio, all with single transition shifts with a doubleoverdrive.

As set forth above, the engagement schedule for the torque-transmittingdevices is shown in the truth table of FIG. 1 b. The chart of FIG. 1 bdescribes the ratio steps that are attained in the above describedtransmission. For example, the step ratio between the first and secondforward speed ratios is 1.61, while the step ratio between the reversespeed ratio and first forward ratio is −0.84.

Referring to FIG. 1 c, the embodiment of powertrain 10 depicted in FIG.1 a is illustrated in a lever diagram format.

The powertrain 10 includes an input member 17, an output member 19, afirst planetary gear set 20A having three nodes: a first node 22A, asecond node 26A and a third node 24A; a second planetary gear set 30Ahaving three nodes: a first node 32A, a second node 36A and a third node34A; a third planetary gear set 40A having three nodes: a first node42A, a second node 46A and a third node 44A.

The input member 17 is continuously connected with the node 42A. Theoutput member 19 is continuously connected with the node 46A. The node22A is continuously connected with the transmission housing 60.

The node 24A is continuously connected with the node 32A viainterconnecting member 70. The node 34A is continuously connected withthe node 44A via interconnecting member 72.

A first torque-transmitting device, such as brake 50 engages the node36A with the transmission housing 60. A second torque-transmittingdevice, such as clutch 52, engages the node 26A with the node 36A. Athird torque-transmitting device, such as clutch 54, engages the node26A with the node 42A. A fourth torque-transmitting device, such asclutch 55, engages the node 26A with the node 46A. A fifthtorque-transmitting device, such as clutch 56, engages the nodes 24A and32A via interconnecting member 70 with the nodes 34A and 44A viainterconnecting member 72. A sixth torque-transmitting device, such asclutch 57, engages the nodes 24A and 32A with the node 46A.

To establish ratios, two torque-transmitting devices are engaged foreach gear state. The engaged torque-transmitting devices are representedby an “X” in each respective row of FIG. 1 b. For example, to establishreverse gear, the brake 50 and clutch 54 are engaged. The brake 50engages the node 36A with the transmission housing 60. The clutch 54engages the node 26A with the node 42A. Likewise, the eight forwardratios are achieved through different combinations of clutch engagementas per FIG. 1 b.

The powertrain 10 (or 110 to be described later) may share componentswith a hybrid vehicle, and such a combination may be operable in a“charge-depleting mode”. For purposes of the present invention, a“charge-depleting mode” is a mode wherein the vehicle is poweredprimarily by an electric motor/generator such that a battery is depletedor nearly depleted when the vehicle reaches its destination. In otherwords, during the charge-depleting mode, the engine 12 is only operatedto the extent necessary to ensure that the battery is not depletedbefore the destination is reached. A conventional hybrid vehicleoperates in a “charge-sustaining mode”, wherein if the battery chargelevel drops below a predetermined level (e.g., 25%) the engine isautomatically run to recharge the battery. Therefore, by operating in acharge-depleting mode, the hybrid vehicle can conserve some or all ofthe fuel that would otherwise be expended to maintain the 25% batterycharge level in a conventional hybrid vehicle. It should be appreciatedthat a hybrid vehicle powertrain is preferably only operated in thecharge-depleting mode if the battery can be recharged after thedestination is reached by plugging it into an energy source.

Description of a Second Exemplary Embodiment

With reference to FIG. 2 a, a powertrain 110 is shown, including aconventional engine and torque converter 12 connected to anotherembodiment of the planetary transmission, designated generally by thenumeral 114, and a conventional final drive mechanism 16.

The planetary transmission 114 includes an input member 17 continuouslyconnected with the engine 112, a planetary gear arrangement 118, and anoutput member 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 118 includes three planetary gearsets 120, 130 and 140.

The planetary gear set 120 includes a sun gear member 122, a ring gearmember 124, and a planet carrier assembly member 126. The planet carrierassembly member 126 includes a plurality of pinion gears 127 rotatablymounted on a carrier member 129 and disposed in meshing relationshipwith both the sun gear member 122 and the ring gear member 124.

The planetary gear set 130 includes a sun gear member 132, a ring gearmember 134, and a planet carrier assembly member 136. The planet carrierassembly member 136 includes a plurality of pinion gears 137 rotatablymounted on a carrier member 139 and disposed in meshing relationshipwith both the ring gear member 134 and the sun gear member 132.

The planetary gear set 140 includes a sun gear member 142, split ringgear member portions 1440, 1441, and a planet carrier assembly member146. The planet carrier assembly member 146 includes a plurality ofpinion gears 147 mounted on a carrier member 149 and disposed in meshingrelationship with both the split ring gear member portions 1440, 1441and the sun gear member 142. The split ring gear member portions 1440,1441 configuration allows a leg of the planet carrier assembly member146 to extend between the split ring gear member portions 1440, 1441.

The input member 17 is continuously connected with the sun gear member132 of the planetary gear set 130. The output member 19 is continuouslyconnected with the split ring gear member portion 1440. The sun gearmember 122 is continuously connected with the transmission housing 160.

A first interconnecting member 170 continuously connects the planetcarrier assembly member 126 with the ring gear member 134. A secondinterconnecting member 172 continuously connects the planet carrierassembly member 136 with the planet carrier assembly member 146.

The planetary gear arrangement also includes six torque-transmittingdevices 150, 152, 154, 155, 156 and 157. The torque-transmitting devices150 and 152 are stationary-type torque-transmitting devices, commonlytermed brakes or reaction clutches. The torque-transmitting devices 154,155, 156 and 157 are rotating-type torque-transmitting devices, commonlytermed clutches.

A first torque-transmitting device, such as brake 150, selectivelyconnects the planet carrier assembly member 146 with the transmissionhousing 160. A second torque-transmitting device, such as brake 152,selectively connects the sun gear member 142 with the transmissionhousing 160. A third torque-transmitting device, such as clutch 154,selectively connects the ring gear member 124 with the split ring gearmember portion 1441. A fourth torque-transmitting device, such as clutch155, selectively connects the planet carrier assembly member 126 withthe split ring gear member portion 1441. A fifth torque-transmittingdevice, such as clutch 156, selectively connects the ring gear member124 with the sun gear member 142. A sixth torque-transmitting device,such as clutch 157, selectively connects the sun gear member 132 withthe planet carrier assembly member 126 and the ring gear member 134 viainterconnecting member 170.

As set forth above, the engagement schedule for the torque-transmittingdevices is shown in the truth table of FIG. 2 b to provide at leasteight forward speed ratios and one reverse speed ratio. As shown anddescribed above for the configuration in FIG. 1 a, those skilled in theart will understand from the respective truth tables how the speedratios are established through the planetary gear sets identified in thewritten description. The chart of FIG. 2 b describes the gear ratios andratio steps that are attained in the above described transmission. Forexample, the step ratio between the first and second forward speedratios is 1.68, while the step ratio between the reverse speed ratio andfirst forward ratio is −0.69.

Referring to FIG. 2 c, the embodiment of powertrain 110 depicted in FIG.2 a is illustrated in a lever diagram format.

The powertrain 110 includes an input member 17, an output member 19, afirst planetary gear set 120A having three nodes: a first node 122A, asecond node 126A and a third node 124A; a second planetary gear set 130Ahaving three nodes: a first node 132A, a second node 136A and a thirdnode 134A; a third planetary gear set 140A having three nodes: a firstnode 142A, a second node 146A and a third node 144A.

The input member 17 is continuously connected with the node 132A. Theoutput member 19 is continuously connected with the node 144A. The node122A is continuously connected with the transmission housing 160.

The node 126A is continuously connected with the node 134A viainterconnecting member 170. The node 136A is continuously connected withthe node 146A via interconnecting member 172.

A first torque-transmitting device, such as brake 150, engages the nodes146A and 136A with the transmission housing 160. A secondtorque-transmitting device, such as brake 152, engages the node 142Awith the transmission housing 160. A third torque-transmitting device,such as clutch 154, engages the node 124A with the node 144A. A fourthtorque-transmitting device, such as clutch 155, engages the nodes 134Aand 126A with the node 144A. A fifth torque-transmitting device, such asclutch 156, engages the node 124A with the node 142A. A sixthtorque-transmitting device, such as clutch 157, engages the node 132Awith the nodes 134A and 126A.

To establish ratios, two torque-transmitting devices are engaged foreach gear state. The engaged torque-transmitting devices are representedby an “X” in each respective row of FIG. 2 b. For example, to establishreverse gear, the brake 150 and clutch 155 are engaged. The brake 150engages the nodes 146A and 136A with the transmission housing 160. Theclutch 155 engages the node 126A and 134A with the node 144A. Likewise,the eight forward ratios are achieved through different combinations ofclutch engagement as per FIG. 2 b.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A multi-speed transmission comprising: an input member; an outputmember; first, second and third planetary gear sets each having first,second and third members; a first interconnecting member continuouslyconnecting a member of said first planetary gear set with a member ofsaid second planetary gear set; a second interconnecting membercontinuously connecting a member of said second planetary gear set witha member of said third planetary gear set; said first member of saidfirst planetary gear set being continuously connected with a stationarymember; and six torque-transmitting devices for selectivelyinterconnecting said members of said planetary gear sets with saidstationary member or other members of said planetary gear sets, said sixtorque-transmitting devices being engaged in combinations of two toestablish at least eight forward speed ratios and at least one reversespeed ratio between said input member and said output member.
 2. Thetransmission of claim 1, wherein a first of said six torque-transmittingdevices is operable for selectively connecting said second member ofsaid second or said third planetary gear set with said stationarymember.
 3. The transmission of claim 2, wherein a second of said sixtorque-transmitting devices is operable for selectively connecting saidsecond member of said first planetary gear set with said second memberof said second planetary gear set or selectively connecting said firstmember of said third planetary gear set with said stationary member. 4.The transmission of claim 3, wherein a third of said sixtorque-transmitting devices is operable for selectively connecting saidsecond member of said first planetary gear set with said first member ofsaid third planetary gear set or selectively connecting said thirdmember of said first planetary gear set with said third member of saidthird planetary gear set.
 5. The transmission of claim 4, wherein afourth of said six torque-transmitting devices is operable forselectively connecting said second member of said first planetary gearset with said second or said third member of said third planetary gearset.
 6. The transmission of claim 5, wherein a fifth of said sixtorque-transmitting devices is operable for selectively connecting saidthird member of said first planetary gear set with said third member ofsaid second planetary gear set or with said first member of said thirdplanetary gear set.
 7. The transmission of claim 6, wherein a sixth ofsaid six torque-transmitting devices is operable for selectivelyconnecting said third member of said first planetary gear set with saidsecond member of said third planetary gear set or selectively connectingsaid first member of said second planetary gear set with said thirdmember of said second planetary gear set.
 8. The transmission of claim1, wherein said first, second and third members of said first, secondand third planetary gear sets comprise a sun gear member, a planetcarrier assembly member and a ring gear member, respectively.
 9. Thetransmission of claim 1, wherein the third member of one of saidplanetary gear sets comprises a split ring gear member to enable aconnection between portions of said split ring gear member to arespective planet carrier assembly member.
 10. The transmission of claim1, wherein said input member is continuously connected with said firstmember of said second or said third planetary gear set; and said outputmember is continuously connected with said second or said third memberof said third planetary gear set.
 11. A multi-speed transmissioncomprising: an input member; an output member; first, second and thirdplanetary gear sets each having first, second and third members; saidinput member being continuously connected with said first member of saidsecond or said third planetary gear set; said output member beingcontinuously connected with said second or said third member of saidthird planetary gear set; a first interconnecting member continuouslyconnecting said second member of said first planetary gear set with saidfirst member of said second planetary gear set or continuouslyconnecting said second member of said first planetary gear set with saidthird member of said second planetary gear set; a second interconnectingmember continuously connecting said third member of said secondplanetary gear set with said third member of said third planetary gearset or continuously connecting said second member of said secondplanetary gear set with said second member of said third planetary gearset; said first member of said first planetary gear set beingcontinuously connected with a stationary member; a firsttorque-transmitting device selectively connecting said second member ofsaid second or said third planetary gear set with said stationarymember; a second torque-transmitting device selectively connecting saidsecond member of said first planetary gear set with said second memberof said second planetary gear set or selectively connecting said firstmember of said third planetary gear set with said stationary member; athird torque-transmitting device selectively connecting said secondmember of said first planetary gear set with said first member of saidthird planetary gear set or selectively connecting said third member ofsaid first planetary gear set with said third member of said thirdplanetary gear set; a fourth torque-transmitting device selectivelyconnecting said second member of said first planetary gear set with saidsecond or said third member of said third planetary gear set; a fifthtorque-transmitting device selectively connecting said third member ofsaid first planetary gear set with said third member of said secondplanetary gear set or with said first member of said third planetarygear set; a sixth torque-transmitting device selectively connecting saidthird member of said first planetary gear set with said second member ofsaid third planetary gear set or selectively connecting said firstmember of said second planetary gear set with said third member of saidsecond planetary gear set; and said six torque-transmitting devicesbeing engaged in combinations of two to establish at least eight forwardspeed ratios and at least one reverse speed ratio between said inputmember and said output member.
 12. The transmission of claim 11, whereinsaid first, second and third members of said first, second and thirdplanetary gear sets comprise a sun gear member, a planet carrierassembly member and a ring gear member, respectively.
 13. Thetransmission of claim 12, wherein said third member of one of saidfirst, second and third planetary gear sets is a split ring gear member.14. A multi-speed transmission comprising: an input member; an outputmember; first, second and third planetary gear sets each having a sungear member, planet carrier assembly member and ring gear member; saidinput member being continuously interconnected with said sun gear memberof said third planetary gear set; said output member being continuouslyinterconnected with said planet carrier assembly member of said thirdplanetary gear set; said sun gear member of said first planetary gearset being continuously connected with a stationary member; a firstinterconnecting member continuously connecting said ring gear member ofsaid first planetary gear set with said sun gear member of said secondplanetary gear set; a second interconnecting member continuouslyconnecting said ring gear member of said second planetary gear set withsaid ring gear member of said third planetary gear set; a firsttorque-transmitting device selectively connecting said planet carrierassembly member of said second planetary gear set with said stationarymember; a second torque-transmitting device selectively connecting saidplanet carrier member of said first planetary gear set with said planetcarrier assembly member of said second planetary gear set; a thirdtorque-transmitting device selectively connecting said planet carrierassembly member of said first planetary gear set with said sun gearmember of said third planetary gear set; a fourth torque-transmittingdevice selectively connecting said planet carrier assembly member ofsaid first planetary gear set with said planet carrier assembly memberof said third planetary gear set; a fifth torque-transmitting deviceselectively connecting said ring gear member of said first planetarygear set with said ring gear member of said second planetary gear set; asixth torque-transmitting device selectively connecting said ring gearmember of said first planetary gear set with said planet carrierassembly member of said third planetary gear set; said sixtorque-transmitting devices being engaged in combinations of two toestablish eight forward speed ratios and one reverse speed ratio betweensaid input member and said output member.
 15. A multi-speed transmissioncomprising: an input member; an output member; first and secondplanetary gear sets each having a sun gear member, planet carrierassembly member, and ring gear member; third planetary gear set having asun gear member, planet carrier assembly member and a split ring gearmember consisting of a first and second portion; said input member beingcontinuously interconnected with said sun gear member of said secondplanetary gear set; said output member being continuously interconnectedwith said first portion of said split ring gear member; said sun gearmember of said first planetary gear set being continuously connectedwith a stationary member; a first interconnecting member continuouslyconnecting said planet carrier assembly member of said first planetarygear set with said ring gear member of said second planetary gear set; asecond interconnecting member continuously connecting said planetcarrier assembly member of said second planetary gear set with saidplanet carrier assembly member of said third planetary gear set; a firsttorque-transmitting device selectively connecting said planet carrierassembly member of said third planetary gear set with said stationarymember; a second torque-transmitting device selectively connecting saidsun gear member of said third planetary gear set with said stationarymember; a third torque-transmitting device selectively connecting saidring gear member of said first planetary gear set with said ring gearmember of said third planetary gear set; a fourth torque-transmittingdevice selectively connecting said planet carrier assembly member ofsaid first planetary gear set with said ring gear member of said thirdplanetary gear set; a fifth torque-transmitting device selectivelyconnecting said ring gear member of said first planetary gear set withsaid sun gear member of said third planetary gear set; a sixthtorque-transmitting device selectively connecting said sun gear memberof said second planetary gear set with said ring gear member of saidsecond planetary gear set; said six torque-transmitting devices beingengaged in combinations of two to establish eight forward speed ratiosand one reverse speed ratio between said input member and said outputmember.